This invention relates to an electrical musical instrument having digital circuitry for producing chordally related tones.
Electronic organs have included circuitry for automatic chord selection and generation of chordally related tone signals. However, use of the chordal tone signals has generally been limited to the audio reproduction thereof. Circuitry for controlling automatic sequential tone generation has been separate from the chordal circuitry, since the function of sequential tone generation has been considered a separate feature functionally unrelated to the chord feature of the electronic organ.
Digital circuitry for producing a sequential series of related tones is known. An accompaniment melody can be played on the lower manual of an electronic organ by manual selection of keys, or by selection of automatic accompaniment circuitry. For example, it is known to provide sequentially enabled gates controlled by an arpeggio circuit or by a strum circuit. It also is known to play, one at a time and in a rhythmic fashion, several related notes associated with selected keys. In an organ effect known as "counter melody", chordally related tones are sequentially played in a rhythmic fashion, with an equal or unequal time interval between tones, in order to simulate various types of melody which can be played on the lower keyboard.
Automatic chord selection in electronic organs has been limited to generation of the root, third, fifth and other standard interval notes. However, a player may manually generate other types of chords such as an inverted chord in which one or more of the notes forming the chord may be octavely displaced with respect to the standard root note. For example, the third interval note may be played in a higher octave than the root note and the fifth note. While electronic organs have allowed an operator to manually generate any type of chord, prior automatic circuits have not allowed processing of complex tone signals such as occur in inverted chords or the like.